1. Field of the Invention
The invention relates to techniques of fabricating by etch a plate-shaped reflective mirror having a reflective surface on which light is incident, and more particularly to techniques of fabricating such a reflective mirror by wet-etch.
2. Description of the Related Art
For example, in the applications where images are formed optically, some situations exist where a plate-shaped reflective mirror is employed which has a reflective surface on which light is incident.
An exemplary type of such a reflective mirror is used for optical scan, in a manner that the reflective mirror is excited to vibrate about its oscillation axis parallel to the reflective surface, to thereby vary a direction in which light is reflected from the reflective surface upon entry thereinto.
There exists an example of a conventional reflective mirror of the aforementioned type (see, for example, Japanese Patent Application Publication No. 2003-57586).
This conventional reflective mirror constitutes an oscillating body in cooperation with a plate-shaped spring which extends from the reflective mirror along the oscillation axis and which is excited to cause at least a torsional vibration about the oscillation axis. This conventional reflective mirror is used for optical scan, in a manner that at least a portion of the oscillating body is excited to vibrate, to thereby vary a direction in which light is reflected from the reflective surface upon entry thereinto.
As disclosed in the aforementioned Japanese Patent Application Publication No. 2003-57586, the above-described conventional reflective mirror is conventionally fabricated so as to have a quadrangular planar-shape having a center line of symmetry coincident with the oscillation axis of the reflective mirror. Further, this conventional reflective mirror is fabricated by etch. In addition, etch is categorized into dry-etch and wet-etch.